A card-swipe for medical tests

October 29, 2008

SALT LAKE CITY - University of Utah scientists successfully created a sensitive prototype device that could test for dozens or even hundreds of diseases simultaneously by acting like a credit card-swipe machine to scan a card loaded with microscopic blood, saliva or urine samples.

The prototype works on the same principle - giant magnetoresistance or GMR - that is used to read data on computer hard drives or listen to tunes on portable digital music players.

"Think how fast your PC reads data on a hard drive, and imagine using the same technology to monitor your health," says Marc Porter, a Utah Science, Technology and Research (USTAR) professor of chemistry, chemical engineering and bioengineering.

Porter is the senior author of a pair of studies demonstrating the new method for rapid disease testing. The research will be published in the Saturday, Nov. 1, 2008, issue of the journal Analytical Chemistry.

"You can envision this as a wellness check in which a patient sample - blood, urine, saliva - is spotted on a sample stick or card, scanned, and then the readout indicates your state of well-being," says USTAR research scientist Michael Granger, a co-author of the research. "We have a great sensor able to look for many disease markers."

Unlike lab tests today, results could be available in minutes, not hours to weeks.

Porter and Granger conducted the research with John Nordling, Rachel Millen and Heather Bullen at Iowa State University in Ames - where Porter once worked - and Mark Tondra, then at NVE Corp., in Eden Prairie, Minn.

The Utah Science, Technology and Research initiative seeks to create new high-tech jobs by recruiting world-class research teams to develop products and services that can be commercialized to start new businesses and stimulate Utah's economy.

Homeland Security, Environmental Monitoring, Veterinary Medicine

The prototype card-swipe device consists of a GMR "read head" and sample stick. Right now, the device is about the size of a PC. But Granger says that when it is developed commercially, the GMR sensor device will look like a credit card reader.

Porter expects a more advanced version will start being used to test farm animals for diseases in about two years, and a version for human medical tests might begin clinical evaluation in five years, perhaps sooner if pursued by certified laboratories.

"We also think it has homeland security applications," Porter says.

A card swipe device could be taken into the field, where a sample card or stick "could be dipped in groundwater, dried off and read in our device to look for E. coli, plague, smallpox or other suspects on the homeland security list," he says.

Granger says cards with GMR sensors also could be used for environmental monitoring of various toxins or toxic chemicals in an office building's water or air.

The new research showed the method was very sensitive, detecting as few as 800 microscopic particles that mimicked disease-related substances.

GMR's capability to detect a single particle of a biological substance "is just over the horizon," which could be used to test blood or other samples for viruses that can cause disease in minute concentrations, Porter says.

Card-swipe testing devices would be inexpensive because they use existing, inexpensive hard-drive technology, Granger says. "The price would be such that small diagnostic labs could buy them, and eventually your local pharmacist could have one," Porter envisions.

Porter says a sample card swiped in a GMR sensor device conceivably could hold 1,900 different samples for testing, but that in most medical settings, less than a dozen tests would be needed. Nevertheless, "you eventually might test for hundreds of proteins or other compounds in the body when profiling a person's health," he says.

Turning Nobel-Winning Knowledge into Medical Technology

The new testing method makes use of "giant magnetoresistance," or GMR, a phenomenon discovered independently in 1988 by Albert Fert of France and Peter Grünberg of Germany. They shared the 2007 Nobel Prize in Physics for the discovery.

Magnetoresistance is the change in a material's resistance to electrical current when an external magnetic field is applied to the material. That change usually is not more than 1 percent. But some multilayer materials display a change in resistance of as much as 80 percent. That is giant magnetoresistance.

Porter says GMR "is an ultrasensitive method to detect magnetic footprints," and is used to read data from computer hard disks and from MP3 music players.

According to the Nobel Foundation: "A hard disk stores information, such as music, in the form of microscopically small areas magnetized in different directions. The information is retrieved by a read-out head that scans the disk and registers the magnetic changes. ... A read-out head based on the GMR effect can convert very small magnetic changes into differences in electrical resistance and therefore into changes in the current emitted by the read-out head. The current is the signal from the read-out head and its different strengths represent ones and zeros."

In the first new study, Porter, Granger and colleagues set the stage for using GMR devices to test medical, environmental or other biological samples.

The prototype reader had four GMR devices: two sensors to detect changes to the magnetic fields of the sample spots, and two "reference elements" to distinguish how magnetic measurements were affected by temperature changes as opposed to the presence of disease indicators in medical samples.

The prototype does not yet look like a credit card reader or card-swipe device. Instead, it is used to "read" a Pyrex glass sample stick about three-quarters-inch long and one-eighth-inch wide. Biological samples can be placed on the sample stick, which then is "scanned much like a credit card reader," Porter says.

In the first study, instead of holding blood or other medical samples, the sample stick had 15 raised spots of iron-nickel "permalloy," a magnetic material that produces a magnetic signature read by GMR sensors.

"We are simulating a signal to test the card-swipe device," Granger says. "It's not a real sample."

The study determined how measurements by the GMR sensors - the heart of a future card-swipe device - can be calibrated to account for variations in the size of the permalloy spots, the amount of separation between the sensors and the sample stick, and the angle of the sample stick as it is scanned by the sensors.

Those factors determine how consistently and accurately a card-swipe device would detect minute amounts of substances associated with diseases.

Simulating a Disease Test

In the second study, the sample stick's alloy spots were replaced by the material that would be used on real medical test cards: microscopic spots or "addresses" of gold that were no longer than the smallest known bacterium. The widths were varied to test which size of addresses could be "read" most accurately.

A substance named biotin or vitamin B-7 was bound chemically to the gold spots on the sample stick. Tiny drops of magnetic particles coated with streptavidin - a protein found in eggs - were placed on the gold spots.

"The gold address has no magnetic signature," Granger says. "Once the particles are bound to it, GMR picks up that magnetic signature. It's a proof of principle."

The experiment was repeated hundreds of times with different concentrations of magnetic particles bound to the biological substance.

"We could detect as few as 800 magnetic particles on an address," Porter says. "We believe that with further development, we can get down to single-particle detection."

The Utah scientists cite examples of how a GMR card reader might be used medically for humans and animals:
For more information on USTAR, see: www.ustar.utah.edu

University of Utah Public Relations
201 Presidents Circle, Room 308
Salt Lake City, Utah 84112-9017
(801) 581-6773 fax: (801) 585-3350

University of Utah

Related Prostate Cancer Articles from Brightsurf:

Low risk of cancer spread on active surveillance for early prostate cancer
Men undergoing active surveillance for prostate cancer have very low rates - one percent or less - of cancer spread (metastases) or death from prostate cancer, according to a recent study published in the Journal of Urology®, an Official Journal of the American Urological Association (AUA).

ESMO 2020: Breast cancer drug set to transform prostate cancer treatment
A drug used to treat breast and ovarian cancer can extend the lives of some men with prostate cancer and should become a new standard treatment for the disease, concludes a major trial which is set to change clinical practice.

Major trial shows breast cancer drug can hit prostate cancer Achilles heel
A drug already licensed for the treatment of breast and ovarian cancers is more effective than targeted hormone therapy at keeping cancer in check in some men with advanced prostate cancer, a major clinical trial reports.

The Lancet: Prostate cancer study finds molecular imaging could transform management of patients with aggressive cancer
Results from a randomised controlled trial involving 300 prostate cancer patients find that a molecular imaging technique is more accurate than conventional medical imaging and recommends the scans be introduced into routine clinical practice.

Common genetic defect in prostate cancer inspires path to new anti-cancer drugs
Researchers found that, in prostate cancer, a mutation leading to the loss of one allele of a tumor suppressor gene known as PPP2R2A is enough to worsen a tumor caused by other mutations.

First prostate cancer therapy to target genes delays cancer progression
For the first time, prostate cancer has been treated based on the genetic makeup of the cancer, resulting in delayed disease progression, delayed time to pain progression, and potentially extending lives in patients with advanced, metastatic prostate cancer, reports a large phase 3 trial.

Men taking medications for enlarged prostate face delays in prostate cancer diagnosis
University of California San Diego School of Medicine researchers report that men treated with medications for benign prostatic hyperplasia (enlarged prostate) experienced a two-year delay in diagnosis of their prostate cancer and were twice as likely to have advanced disease upon diagnosis.

CNIO researchers confirm links between aggressive prostate cancer and hereditary breast cancer
The study has potential implications for families with members suffering from these types of tumours who are at an increased risk of developing cancer.

Distinguishing fatal prostate cancer from 'manageable' cancer now possible
Scientists at the University of York have found a way of distinguishing between fatal prostate cancer and manageable cancer, which could reduce unnecessary surgeries and radiotherapy.

Researchers find prostate cancer drug byproduct can fuel cancer cells
A genetic anomaly in certain men with prostate cancer may impact their response to common drugs used to treat the disease, according to new research at Cleveland Clinic.

Read More: Prostate Cancer News and Prostate Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.